I. Field
The following description relates generally to wireless communications systems and more particularly to communication of network signaled values.
II. Background
Wireless communication systems are widely deployed to provide various types of communication content, such as voice, data, video, and so forth, and to communicate information regardless of where a user is located (e.g., inside or outside a structure) and whether a user is stationary or moving (e.g., in a vehicle, walking). These systems may be multiple-access systems capable of supporting communication with multiple users by sharing available systems resources (e.g., bandwidth and transmit power). Multiple-access systems include Frequency Division Multiple Access (FDMA) systems, Time Division Multiple Access (TDMA) systems, Code Division Multiple Access (CDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems, and others.
Generally, wireless multiple-access communication systems can simultaneously support communication for multiple mobile devices. Each mobile device can communicate with one or more base stations through transmissions on forward and reverse links. Forward link (or downlink) refers to the communication link from base stations to mobile devices. Reverse link (or uplink) refers to the communication link from mobile devices to base stations. These communication links can be established through single-input-single-output (SISO) systems, multiple-input-single-output (MISO) systems, multiple-input-multiple-output (MIMO) systems, and so forth. In addition, mobile devices can communicate with other mobile devices (and/or base stations with other base stations) in peer-to-peer wireless network configurations.
An orthogonal frequency division multiplex (OFDM) communication system effectively partitions the overall system bandwidth into multiple subcarriers, which may also be referred to as frequency sub-channels, tones, or frequency bins. For an OFDM system, the data to be transmitted (e.g., the information bits) is first encoded with a particular coding scheme to generate coded bits, and the coded bits are further grouped into multi-bit symbols that are then mapped to modulation symbols. Each modulation symbol corresponds to a point in a signal constellation defined by a particular modulation scheme (e.g., M-PSK or M-QAM) used for data transmission. At each time interval, which may be dependent on the bandwidth of each frequency subcarrier, a modulation symbol may be transmitted on each of the frequency subcarriers. Thus, OFDM may be used to combat inter-symbol interference (ISI) caused by frequency selective fading, which is characterized by different amounts of attenuation across the system bandwidth.
A MIMO system employs multiple (NT) transmit antennas and multiple (NR) receive antennas for data transmission. A MIMO channel formed by the NT transmit and NR receive antennas may be decomposed into Nz independent channels, which are also referred to as spatial channels. Generally, each of the Nz independent channels corresponds to a dimension. The MIMO system can provide improved performance (e.g., higher throughput and/or greater reliability) if the additional dimensionalities created by the multiple transmit and receive antennas are utilized. A MIMO system also supports time division duplex (TDD) and frequency division duplex (FDD) systems. In a TDD system, forward and reverse link transmissions are on the same frequency region so that the reciprocity principle allows estimation of the forward link channel from the reverse link channel. This enables an access point to extract transmit beam-forming gain on the forward link when multiple antennas are available at the access point.
Further, spectrum emissions masks (SEM) are defined in wireless standards, such as 3GPP, to support coexistence between communications systems operating in the same frequency band. In certain bands, some existing systems have tighter interference requirements and, therefore, wireless standards support SEMs other than those generally defined. For example, in 3GPP, additional SEMs are signaled by the network in system information block (SIB) messages as network signaled (NS) values (e.g., NS—01x). A mobile device that receives and decodes the SIB adjusts its emissions according to the NS values. In current systems, support of defined NS values is mandatory for all devices operating in a spectrum (e.g., that support the frequency band).
In addition, current procedures for signaling SEMs (and system parameters generally) support the signaling of base values (e.g., main values) and additional values of system parameters in information elements (IEs) of SIBs. Such procedures assume that the additional value is a subset or an enhanced value of the base value and cannot be signaled as a base value.